Natural Calendar February 2008

Natural Calendar - February 2008

The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month. We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips, prominent wildflowers and anything else that comes to mind. We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations. If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

Note: You can click on the hyperlinks to learn more about some of the featured items. To return to the Calendar, hit the "back" button on your browser, NOT the "back" button on the web page. All charts are available in a "printer friendly" mode, with black stars on a white background. Left clicking on each chart will take you to a printable black and white image.

Notes and Images From January 2008

Top Image: The Horsehead Nebula, January 3rd and 4th, ST-2000XCM CCD Camera and Televue 85 Refractor. Total exposure time about 4 hours. Bottom Image: The Orion Nebula, January 12th, ST-2000XCM CCD Camera and Televue 85 Refractor. Total exposure time 45minutes.

The bright stars of Orion shine brilliantly on these frosty winter evenings. Few constellations provide as many stellar vistas on so many different scales. The upper image shown is in the vicinity of Orion’s belt, and the lower image is only a few degrees away in the vicinity of Orion’s sword.

The scale of both images is identical, and each image is about two full moons high by a little less than three full moons wide. Both detail portions of the Orion Molecular Cloud Complex that spans most of the constellation.

The upper image of the Horsehead Nebula was taken on January 3^rd and 4^th, and has a total exposure time of about 4 hours. The brightest star in the image is Alnitak, one of the three bright stars that form Orion’s belt. It is the belt star closest to the horizon when the constellation is low in the eastern sky. Three types of nebulosity are visible in the image. The reddish nebulae are emission nebulae, and glow in the light of the hydrogen alpha wavelength, 656nm. The bluish reflection nebulae shine by reflected starlight. The Horsehead Nebula is a dark nebula composed of thick dust that absorbs light. The newest distance estimates of the Orion Molecular Cloud Complex place it about 1350 light-years away.

The image of the Orion Nebula was taken on January 12^th, and has a total exposure of 45 minutes. Clouds moved in and drew a close to the imaging session after that. The high-altitude haze present provided the bluish halos around the bright stars in the image.

Sky Events for February 2008:

Evening Sky:

Total Lunar Eclipse, October 27th, 2004, Nikon D-70 Camera and 6" Apochromatic Refractor

Try not to miss the total lunar eclipse that occurs on February 20th. It is the last total lunar eclipse for almost three years. The moon enters the dark part of the earth's shadow, the umbra, at 7:43pm CST. Be sure and stay up at least until the beginning of the total phase, which occurs at 9:00pm CST. The sight of a deep copper-colored moon in full eclipse is a sight never to be forgotten. The fully eclipsed moon is illuminated by the combined sunsets and sunrises around the earth. Totality lasts until 9:52pm CST. The moon finally exits the umbra at 11:09pm CST.

Mars still shines brightly in Taurus, but is fading quickly as the earth pulls away.

Saturn rises at dusk below the bright star Regulus in Leo. If you wait until it has climbed high in sky, you will be treated to a stunning view in just about any telescope.

Morning Sky:

Venus and Jupiter start the month quite close to each other in the dawn sky. As the month progresses the two planets draw slowly apart. Jupiter climbs higher in the sky while Venus sinks into the dawn glow. Venus is much the brighter of the two.

Mercury becomes visible in the dawn sky around mid-month. By February 27th, it is a little over 1 degree above much brighter Venus.

All times noted in the Sky Events are for Franklin, Tennessee and are Central Standard Time. These times should be pretty close anywhere in the mid-state area.

Constellations: The views below show the sky looking east at 9:00pm CST on February 15^th. The first view shows the sky with the constellation outlines and names depicted. Star and planet names are in yellow. Constellation names are in green. The second view shows the same scene without labels. Leo, the Lion, is prominent with its bright star Regulus. Below Regulus is the bright planet Saturn. Use Regulus and Saturn to guide you to the faint constellation of Sextans, the Sextant. Conspicuous in the northeast is Ursa Major, the Great Bear. The constellations of Bootes, the Herdsman, Coma Berenices, Berenice's Hair, Virgo, the Virgin and Crater, the Cup are all just making their way above the horizon and will be seen better next month. If you can't wait, you can always stay up a little later and watch them rise.

February 15th, 9:00pm, Looking East

All times noted in the Sky Events are for Franklin, Tennessee and are Central Standard Time. These times should be pretty close anywhere in the mid-state area.

On Learning the Constellations: We advise learning a few constellations each month, and then following them through the seasons. Once you associate a particular constellation coming over the eastern horizon at a certain time of year, you may start thinking about it like an old friend, looking forward to its arrival each season. The stars in the evening scene above, for instance, will always be in the same place relative to the horizon at the same time and date each February. Of course, the planets do move slowly through the constellations, but with practice you will learn to identify them from their appearance. In particular, learn the brightest stars (like Regulus in the above scene looking east), for they will guide you to the fainter stars. Once you can locate the more prominent constellations, you can "branch out" to other constellations around them. It may take you a little while to get a sense of scale, to translate what you see on the computer screen or what you see on the page of a book to what you see in the sky. Look for patterns, like the stars of the "Big Dipper."

The earth's rotation causes the constellations to appear to move across the sky just as the sun and the moon appear to do. If you go outside earlier than the time shown on the charts, the constellations will be lower to the eastern horizon. If you observe later, they will have climbed higher.

As each season progresses, the earth's motion around the sun causes the constellations to appear a little farther towards the west each night for any given time of night. If you want to see where the constellations in the above figures will be on March 15th at 9:00pm CST, you can stay up till 11:00pm CST on the February 15th and get a preview. The westward motion of the constellations is equivalent to two hours per month. For instance, if you want to see what stars will be on your eastern horizon on May 15th at 9:00pm CST (3 months from now), you would need to get up at 3:00am CST on February 15th (3 months times 2 hours/month = 6 hours).

Sky Publishing has just come out with a beautiful and compact star atlas, Sky & Telescope's Pocket Star Atlas. It is destined to become a classic, and is a joy to use at the telescope.

A good book to learn the constellations is H. A. Rey's classic, The Stars, A New Way to See Them. Rey's depictions of the constellations and witty commentary are terrific.

A good general reference book on astronomy is the Peterson Field Guide, A Field Guide to the Stars and Planets, by Pasachoff. The book retails for around $14.00.

Starry Night has several software programs for learning the night sky. Visit the Starry Night web site at www.starrynight.com for details.

Amphibians:

Crawfish Frog

The amphibian season continues to build in February. One trick to finding amphibians in winter is to go out on mild (50 degrees Fahrenheit or warmer) rainy nights. For safety, it is important that you have another person with you to help watch for traffic as you slowly drive the back roads. Look for things that cross the road in front of you and stop frequently and listen. Early breeding frogs like Southeastern Chorus Frogs, Spring Peepers and Wood Frogs are already calling by the first of the month. I've also already heard Southern Leopard Frogs calling this year. Spotted Salamanders and Tiger Salamanders also breed in January and February, and the eggs of both can often be found this time of year. Towards the end of the month, given mild temperatures, you can sometimes hear American Toads beginning to call. In west Tennessee, Crawfish Frogs give their loud snoring calls starting in late February and continuing on into early March. At higher elevations, listen for Mountain Chorus Frogs towards the end of the month. Remember that on mild nights you may find frogs and toads out foraging that you do not hear until later in the season.

Birds:

Many times when we have been out looking for amphibians in February we've witnessed courtship flights of the American Woodcock. Listen for the "peent" call at dusk and watch as the male Woodcock spirals upward till it's almost out of sight, then dives back to the ground, twisting and turning. For more about watching American Woodcocks see, "The Woodcock's Call."

Red-Shouldered Hawks mate as early as February in Tennessee. Watch for courtship activities of these and other hawks.

Stick Nests: With the leaves down, this is a great time of year to find raptor stick nests. I make notes of all the nests I find and then periodically check them to see if anyone has "moved in." Many times Great Horned Owls make use of an old Red-Tailed Hawk's nest from the previous year. The owls can already be incubating eggs in January. Of the hawks, Arthur Cleveland Bent, in his "Life Histories of North American Birds of Prey," writes,

"[Red-tailed Hawks]...begin their nest building late in February or early in March; I have seen a wholly new nest half completed and decorated with green pine twigs and down as early as February 18th, over a month before the eggs are laid...Typical nests are from 28 to 30 inches in outside diameter, the inner cavity being 14 or 15 inches wide and 4 or 5 inches deep...The nests are well made of sticks and twigs, half an inch or less in thickness, and neatly lined with strips of inner bark, of cedar, grapevine or chestnut, usnea, and usually at least a few green sprigs of pine, cedar or hemlock. Some nests are profusely and beautifully lined with fresh green sprigs of white pine, which are frequently renewed during incubation and during the earlier stages of growth of the young...They "stake out their claim" late in February or early in March...by marking the nest they propose to use with a sprig of green pine...I believe that the birds prefer to build a new nest each year, but they sometimes use the same nest for consecutive years..."

Bent was writing about the Red-Tail Hawks in New England, so our times could be a little earlier.

You probably have already put out your bird feeders, but if you haven’t you're missing out on a lot of good looks at winter feeder birds. This is a great time of year to start learning your birds. Watch and listen for winter residents such as White-throated and White-crowned Sparrows, Yellow-bellied Sapsuckers, Red-breasted Nuthatches, Golden-crowned Kinglets and Brown Creepers.

Recommended:

Bird Finding in Tennessee, Michael Lee Bierly. A classic guide to finding birds in Tennessee.

The Sibley Guide to Birds, David Allen Sibley

The Sibley Guide to Birds of Eastern North America, David Allen Sibley

This new Sibley Guide covers only eastern North America, is quite compact, and is less expensive than the larger Sibley.

An inexpensive guide for beginners is the Golden Guide for Birds.